U.S. Pat. No. 4,663,725, which is assigned to the same assignee as the present application, discloses the use of microprocessor based refrigeration control for use with a refrigerated container, with the refrigerant compressor being driven by an electric motor. One of the features of this patent is the ability to manually select return air control or discharge air control, with a failure of the temperature sensor associated with the selected control resulting in automatically switching to the other of the two types of control. If the sensors associated with both types of control fail, the unit is shut down.
It is an object of the present invention to expand upon and improve the protective features of the aforesaid patent, while extending microprocessor control to transport refrigeration systems in which the prime mover is selectable between an internal combustion engine, such as a Diesel engine, and a stand-by electric motor.